A switch has been installed around a steering wheel of an automobile for controlling electronic devices such as an audio device or an air conditioner with a driver taking the wheel. The switch is called “steering switch” and widely used in recent years, so that the market requires the steering switch easy to operate and free from an operating error. Such a conventional switch as discussed above and the manufacturing method thereof are illustrated in FIG. 9-FIG. 11.
FIG. 9 shows an exploded perspective view of the conventional switch, which includes operating units 1-3 shaped like a box and made of insulating resin, and housing 4 also made of insulating resin. Housing 4 has a plurality of through holes 4A (three holes are shown in FIG. 9), and operating units 1, 2 are put in upper (on the right side in FIG. 9) and middle holes 4A respectively such that each one of operating units 1 and 2 can rock to either side on its center as a fulcrum. Operating unit 3 is put in lower hole 4A (on the left side in FIG. 9) such that it can move up and down.
Each one of operating units 1-3 is formed of a translucent section in light color such as white or milky white, and a non-translucent section in dark color such as black. The non-translucent section covers the surface of the translucent section. On the top face of each one of operating units 1-3, the non-translucent section is removed such that the translucent section is exposed to form display section 1A-3A display a letter, a symbol or a pattern. Display sections 1A-3A show the marks such as “+”, “−”, “”, “” and “MODE”. A light shooting behind the translucent sections will make these marks visible.
Wired board 5 having wiring patterns (not shown) on both faces is disposed under operating units 1-3. On the top face of wired board 5, a plurality of push switches 6 (five push switches are shown in FIG. 9) are mounted with their operating shafts 6A projecting upward, so that switch contacts are formed. A plurality of light emitting elements 7 (three elements are shown in FIG. 9) such as LEDs are mounted also on the top face of wired board 5. Switch 8 is thus formed.
FIG. 10A-FIG. 10C show perspective views illustrating step 1 through step 3 of the manufacturing method of this operating unit 1. Foregoing operating units 1-3 can be manufactured this way: As shown in FIG. 10A, firstly form the translucent section, then cover it with the non translucent section by painting its surface, thereby completing operating unit 1. Then insert operating unit 1 into holder 9A of which exterior is somewhat smaller than the inner circumference of operating unit 1. A plurality of operating units 1 (four units are shown in FIG. 10B) are thus placed on the top face of holding plate 9 as shown in FIG. 10B.
Then a laser beam device (not shown) shoots a laser beam to the plurality of operating units 1 on their top faces sequentially for removing the non-translucent section from the translucent section in order to expose parts of the translucent section, thereby forming display section 1A showing letters, marks, or patterns such as “+” and “−” as shown in FIG. 10C.
In a similar way, display section 2A showing the marks of “”, “” is formed on operating unit 2, and display section 3A showing the letters of “MODE” is formed on operating unit 3. These units are then removed from holding plate 9 and packed in, e.g. bags in a given quantity for storage and transportation purposes.
Operating units 1-3 having the display sections which show different marks as discussed above are put into through holes 4A bored on housing 4 at an upper section (right side in FIG. 9), a middle section, and a lower section (left side in FIG. 9), then wired board 5, to which a plurality of push switches and light emitting elements 7 are mounted, is mounted to housing 4, thereby completing switch 8.
FIG. 11 shows a plan view of a steering wheel incorporating the foregoing conventional switch.
Switch 8 thus structured is mounted to steering wheel 11 at spokes 13 on both sides near to wheel 11. These spokes 13 are located between steering wheel 11 and pad 12 that is placed at the center and containing an airbag. The plurality of push switches 6 and light emitting elements 7 are coupled to electronic circuits of the automobile via the wired pattern of wired board 5, connectors, and lead wires (not shown), so that switch 8 is mounted to the automobile.
The foregoing structure allows the driver to depress with his/her finger, e.g., operating unit 1 on its right side where “+” is marked while the driver keeps taking wheel 11 and extends his/her finger for depressing. Operating unit 1 then rocks on its center as a fulcrum, and the underside of operating unit 1 depresses shaft 6A for electrically switching on/off push switch 6 placed under the right side of operating unit 1.
This instance tells that the center of operating unit 1 is fixed by engaging the recess on the lateral face of operating unit 1 with the protrusion on the lateral face of hole 4A, and depression on operating unit 1 at its either side allows operating unit 1 to rock either side on its center as a fulcrum, so that push switch 6 placed under operating unit 1 is switched on or off. This movement is called rocking motion, and such operation is called rocking operation.
The electronic circuits mounted to the automobile control the devices installed to the automobile in response to electrical switch-on/off of push switches 6. For instance, the audio device mounted in the automobile increases its sound volume.
The rocking operation done to operating unit 1 on the left side, where “−” is marked, allows operation unit 1 to rock to the other side of the rocking operation done on “+” mark, and push switch 6 placed under the left side of operating unit 1 is switched on/off, so that the sound volume of the audio device decreases.
Rocking operation done to operating unit 2, where “”“” are marked, allows controlling a temperature of an air conditioner installed in the automobile. Rocking operation to operating unit 3, where “MODE” is displayed, allows controlling switchover of a mode of a given device mounted in the automobile.
To sum up, switch 8 mounted near steering wheel 11 allows the driver to maneuver operating units 1-3 by using, e.g., only his/her thumb for controlling the devices in the automobile while the driver keeps taking steering wheel 11. This structure thus allows the driver to operate the devices with ease while the driver sits at the wheel.
In the dark environment, e.g. in the night, operation of a given switch (not shown) prompts light emitting elements 7 to emit light and illuminate display sections 1A-3A of operating units 1-3, so that the driver can identify the respective operating units with ease even in the dark environment.
Unexamined Japanese Patent Publication No. 2005-317236 is known as prior art of the present invention.
The conventional switch discussed above; however, has the following problems: A laser beam is shot to the top face of each one of operating units 1-3 for removing the non translucent section in a given shape, thereby forming display sections 1A-3A. In this case, a positional deviation of display sections 1A-3A sometimes occurs due to measurement dispersion in operating units 1-3 or wobble between holders 9A and operating units 1-3.
When operating units 1-3 having different display marks are mounted to housing 4, visual check is needed on respective marks, and inserting them into upper, middle, and lower holes 4A without errors in the order of arrangement. This assembly work thus takes a time, and the switch becomes expensive.